Astronauts on the moon would face nearly three times more radiation exposure than those aboard the International Space Station, which could make long-term missions riskier than thought.
“Once you’ve survived being on the moon and come back to Earth, radiation damage is what stays with you for the rest of your life and that’s why this is a critical measurement,” says Robert Wimmer-Schweingruber at the University of Kiel in Germany.
Wimmer-Schweingruber and his team analysed several weeks of data acquired by China’s Chang’e 4 lander, which became the first spacecraft to land on the far side of the moon last year. “Part of the reason for this mission and other missions to the moon is preparing for human presence ,” he says.
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But the high levels of radiation detected present an additional challenge for future long-term lunar missions, says Wimmer-Schweingruber. “The radiation we see right now is pretty high energy and shielding against that is difficult.”
Wimmer-Schweingruber and his colleagues discovered that levels of radiation exposure on the moon were between 200 and 1000 times higher than on Earth’s surface – equivalent to levels of exposure five to 10 times those experienced during a flight from New York to Frankfurt, or about 2.6 times higher than those experienced by astronauts on the International Space Station.
“What astonished us was the amount of neutron radiation, which is due to neutrons and gamma rays,” says Wimmer-Schweingruber. “That’s something we’re investigating further.”
“There is still uncertainty on whether this increased level of exposure to heavy-charged particle radiation will have significant short and long-term impacts [on] human health,” says Jeff Chancellor at Louisiana State University.
“Knowing the average amount of radiation an astronaut on the surface of the moon would be exposed to – and how that average can change over time – will make it much easier to plan future human exploration of the moon in such a way that the risk of harm to the astronauts is minimised,” says Tessa Fisher at Arizona State University.
“If you wanted to live on the surface of the moon, you’d want to dig down pretty deep or cover yourself with a lot of lunar dirt,” says Wimmer-Schweingruber. He estimates that astronauts staying on the moon for two or three months would need a habitat covered with an 80-centimetre thick layer of lunar dirt to protect them.
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